On March 14 the EU will vote on the use of neonicotinoids in pest control products. The threat of the ban, along with fears about the chemicals' side effects, has already prompted Homebase and B&Q to remove products from their shelves.

Neonicotinoid chemicals used in pesticides to kill bugs such as vine weevil, aphids and whitefly have been implicated as damaging to bees by several scientific studies, as well as the EU risk assessment body, the European Food Safety Authority.

The EFSA says that imidacloprid and clothianidin, made by Bayer, and thiamethoxam, made by Syngenta, can kill bees feeding on flowering crops. This follows studies by the University of Stirling and by French scientists that found that bees consuming neonicotinoids suffered an 85 per cent loss in the number of queens. There was also a doubling in the number of "disappeared" bees that were lost while foraging.

Paul de Zylva, senior campaigner with Friends of the Earth, says that almost 1,000 garden retailers have removed products after campaigns by FOE and others. It is still the case, however, that many plants sold at garden centres will have received a dose of one of these products prior to sale to control vine weevil.

"Public confidence has waned around the issue of pesticides," says de Zylva. "This is not too dissimilar to the way the public feels about supermarkets and horsemeat. They feel let down."

De Zylva believes neonicotinoids have "not been tested properly on wild bumblebees or solitary bees. The science has moved on. The manufacturers say the testing has been done, but it hasn't."

Garden Organic is among many groups that have supported FOE in its Bee Cause campaign – but for the industry, the issue is far from black and white. Neonicotinoids do undoubtedly protect crop yields against pests – and the harm they do has yet to be unequivocally proven. The British Bee Keepers Association (BBKA), for example, has concerns that restrictions on neonicotinoids could have a negative knock-on effect on bee health. "Growers will inevitably continue to use pesticides and may have no alternative but to return to the use of older, more dangerous products," says a spokesman.

Many older products have been banned already, however, which raises questions about how growers – professional and amateur – would continue to maximise crop yields.

The BBKA and many industry bodies have called for more field research before any action is taken. At a Bumble Bee Conservation Trust event, the chairman, Professor Michael Usher, supported ongoing neonicotinoid use. "We need pollinating insects but we need our crops too," he said.

The Department for Environment, Food and Rural Affairs (Defra) has also defended these chemicals, which are mainly used on commercial crops such as oil seed rape. Ornamental horticulture accounts for just 0.03 per cent of usage. The government line, followed by industry bodies such as the National Farmers Union as well as manufacturers and suppliers, is that the science behind the reputed threat to bees is not robust.

The NFU horticulture adviser Dr Chris Hartfield says: "Action taken by retailers to remove products containing neonicotinoids from their shelves is a business decision they are perfectly entitled to make. But it does not change the fact there is still no clear evidence showing that neonicotinoids are the cause of the decline in bee populations."

From 1955 to 1972 the veteran garden writer Dr David Hessayon was chief scientist at PBI, which is now part of Bayer, a producer of neonicotinoid chemicals.

"If the scientific analysis of the evidence indicates significant danger to bees, the neonicotinoids must go," he says. "But we have had bans in the past arising from pressures outside objective scientific study. EU pressure resulted in the ban on sulphur and derris, green pressure resulted in the ban on DDT for malaria control. At times we have forgotten it is the dose which makes the poison. For example, if you ate 25lb of chocolate, it could kill you."

Hessayon also referred to the horsemeat scandal: "There's concern about the possibility of bute being in horsemeat, but it's reported that you would have to eat 600 hamburgers to reach the level found in a single dose. What could happen in practice should be the basic question."

Whatever the outcome of the vote on March 14, don't expect to have heard the last on the subject. The decline of bees is an emotive issue, but so is the price of food. Any decision that threatens either of these things is bound to be controversial – with or without conclusive scientific evidence.